Blades for wind power generation currently used is mainly made of glass fiber reinforced plastics (GFRP), and the blade itself is an insulator and has no electrical conductivity. Accordingly, in an era when a small wind power generator was used, it was considered that the blade was not struck by lightning. However, as the wind power generator grows in size, damage of the blade struck by the lightning is increased. Accordingly, a method of attaching a member (e.g., lightning receptor) made of metal to the blade and connecting a lead line (e.g., down conductor) to the metallic member so as to lead the lightning to the ground has been generalized (for example, refer to Background-Art section of Patent Literature 1).
Various shapes or types of the lightning receptors have been proposed and put to practical use. For example, Patent Literature 2 proposes a lightning protection structure including a lightning rod protruding from a surface of a tip end of the blade. Patent Literature 3 proposes a lightning protection structure including a rod-shaped lighting receptor embedded in the tip end of the blade.
However, with the shapes of the lightning receptors proposed by Patent Literatures 2 and 3, a damage around the lightning receptor and of the lightning receptor itself due to lightning strike may not be restrained. For this reason, as shown in FIG. 6, there have been proposed a lightning protection structure in which a lightning receptor 20 made of metal, such as aluminum, is provided at a tip end portion of a blade 22 along the shape of the blade, and an anchor part 21, which is provided on the lightning receptor 20, is fixed to the blade 22. There have also been proposed a lightning protection structure in which a lightning receptor made of copper is installed on a portion near the widest width portion of the blade.